1. Field of the Invention
This invention generally relates to a beam-combining laser beam source device wherein laser beams, produced by a plurality of laser beam sources such as semiconductor lasers which have a low power output, are combined so as to multiply the power of the individual lasers. This invention particularly relates to a beam-combining laser beam source device wherein positions of laser beams are adjusted easily in order to combine the laser beams.
2. Description of the Prior Art
Light beam scanning apparatuses, wherein a laser beam is deflected by a light deflector in order to scan a surface with the laser beam, have heretofore been widely used in, for example, scanning recording apparatuses and scanning read-out apparatuses. In such light beam scanning apparatuses, it is desired that a plurality of laser beams be combined so as to obtain laser beams having a high intensity and those laser beams having a high intensity be used as scanning light in order to, for example, increase the speed at which the information recorded on a surface to be scanned is recorded or read out. Combination cf the laser beams is required particularly when semiconductor lasers are used as the laser beam sources. Specifically, a semiconductor laser has various advantages over a gas laser or the like in that the semiconductor laser is small in size, cheap and consumes little power, and that the laser beam can be modulated directly when the drive current applied to the semiconductor laser is changed.
However, the output power of the semiconductor laser is low (20 mW to 30 mW) when the semiconductor laser is operated in order to continuously radiate the laser beam. Therefore, the semiconductor laser is not suitable for use in a light beam scanning apparatus wherein scanning light having a high energy is necessary, for example: a scanning recording apparatus wherein information is recorded on a recording material which has a low sensitivity, such as a draw material (a metal film, an amorphous film, or the like).
On the other hand, when certain kinds of phosphors are exposed to radiation such as X-rays, .alpha.rays, .beta.-rays, .gamma.-rays, cathode rays or ultraviolet rays, they store part of the energy of the radiation. Then, when the phosphor which has been exposed to the radiation is exposed to stimulating rays such as visible light, light is emitted by the phosphor in proportion to the amount of energy stored during exposure to the radiation. A phosphor exhibiting such properties is referred to as a stimulable phosphor. In U.S. Pat. Nos. 4,258,264, 4,276,473, 4,315,318 and 4,387,428 and Japanese Unexamined Patent Publication No. 56(1981)-11395, using a stimulable phosphor in a radiation image recording and reproducing system was proposed. Specifically, a sheet provided with a layer of the stimulable phosphor (hereinafter referred to as a stimulable phosphor sheet) is first exposed to radiation which has passed through an object such as the human body in order to store a radiation image of the object thereon, and is then scanned with stimulating rays such as a laser beam which cause it to emit light in proportion to the amount of energy stored during exposure to the radiation. The light emitted by the stimulable phosphor sheet upon stimulation thereof is photoelectrically detected and converted into an electric image signal, and the image signal is used to reproduce the radiation image of the object as a visible image on a recording material such as photographic film, a display device such as a cathode ray tube (CRT), or the like.
In the aforesaid radiation image recording and reproducing system, it is desired to use a light beam scanning apparatus, wherein a semiconductor laser is used, in order to scan the stimulable phosphor sheet on which a radiation image has been stored, and to thereby read out the radiation image. However, in order to quickly read out the radiation image from the stimulable phosphor sheet, it is necessary to irradiate stimulating rays having a sufficiently high energy onto the stimulable phosphor sheet. Accordingly, it is not always possible to use a light beam scanning apparatus, wherein a semiconductor laser is used, in order to read out an image in the radiation image recording and reproducing system.
In order to obtain a scanning laser beam having a sufficiently high energy from a semiconductor laser, or the like, having a low power outputs, a plurality of laser beam sources may be used, and laser beams radiated from the laser beam sources may be combined so as to multiply the power of the individual laser beam sources.
In general, in order to combine the laser beams produced by a plurality of laser beam sources, the laser beams produced by the laser beam sources are collimated respectively by collimator lenses, guided along optical paths parallel and close to one another, and converged to a common spot by a converging lens. Therefore, in order to accurately combine the laser beams, it is necessary to control the positions of the laser beams before they impinge upon the converging lens, so that they are accurately collimated and positioned along predetermined optical paths close to one another. In general, in order to control the positions of the laser beams, the positions of the respective collimator lenses are finely adjusted.
However, in cases where the collimator lenses corresponding to the respective laser beams to be combined are moved in order to adjust the positions of the laser beams, position adjustment must be carried out for the same number of the collimator lenses as the number of the laser beam sources. Therefore, much time and labor are required to adjust the positions. Also, because the position adjustment must be carried out in three directions for each of the collimator lenses very complicated, expensive mechanisms must be provided to move the respective collimator lenses in three directions.